Insulin-mediated vasodilation and glucose uptake are independently related to fasting serum nonesterified fatty acids in elderly men.

Abstract

OBJECTIVES: To investigate candidate predictors for insulin sensitivity in healthy elderly males, with special reference to the influence of insulin-mediated skeletal muscle blood flow and serum nonesterified fatty acids (NEFA). SUBJECTS: From the participants in a health survey of 70-year-old males, focusing on cardiovascular risk factors, a subgroup of 46 men was sampled. Only men who declared themselves healthy and without medication were included. INTERVENTIONS: Insulin sensitivity was measured with the euglycaemic hyperinsulinaemic clamp. Leg blood flow was measured before and during the clamp, using the Doppler ultrasound technique. RESULTS: Hyperinsulinaemia [steady-state plasma insulin 105(15) mU L-1] increased leg blood flow by 10% (P < 0.004). When tested in bivariate analysis incremental leg blood flow was only significantly related to the serum NEFA concentration (r = - 0.38, P < 0.01) amongst a number of measured variables. Insulin-mediated glucose disposal was related to body mass index (BMI) (r = -0.49, P = 0. 0006), waist/hip ratio (r = - 0.31, P = 0.036), NEFA (r = - 0.50, P = 0.0004) and heart rate (r = - 0.34, P = 0.02). In multivariate analysis only BMI and NEFA remained significantly related to whole-body glucose uptake. CONCLUSIONS: The study demonstrates that in elderly men BMI and fasting serum NEFA but not insulin-induced vasodilation are related to insulin sensitivity. High fasting levels of NEFA relate to both impaired insulin-mediated vasodilation and impaired glucose disposal, respectively. These two insulin actions were not interrelated, however, a finding which may indicate dissociated mechanisms.